1. Field of the Invention
The present invention relates to a disposition structure for a curtain airbag system that deploys an airbag in a vertical direction from a roof side rail in the event of a side impact or a rollover of a motor vehicle.
2. Description of the Related Art
Motor vehicles have recently been equipped with a curtain airbag system that protects an occupant by deploying an airbag in a vertical direction from a roof side rail in the event of a side impact or a rollover.
Such an airbag of the curtain airbag system is retracted in a folded state and disposed at along the roof side rail, and a passenger compartment side of the airbag is covered with an end of a roof trim. In the retracted state, an upper end of a pillar trim, such as a center pillar trim and a quarter pillar trim, is overlaid on an edge of the end of the roof trim from the passenger compartment side.
In the event of the deployment, the curtain airbag system causes the airbag to urge the end of the roof trim toward the inside of the passenger compartment so that the airbag may deploy in a vertical direction through a gap produced between the deformed end and the upper end of a side glass and pillar trim.
However, the pillar trim is typically made of a hard member compared with the roof trim, specifically a hard synthetic resin, in order to prevent deformation or damage caused by being bumped by an occupant or luggage. Such a synthetic resin tends to become harder and easily crack especially at low ambient temperatures. For this reason, an upper end of the pillar trim may be broken when the rapidly inflating airbag hits into the portion. As a result, debris of the pillar trim may be scattered across the compartment.
In order to prevent this problem, Japanese Unexamined Patent Application Publication (JP-A) No. 2008-230474 discloses a curtain airbag system provided with an airbag guide that is deployed so as to cover an upper end of a pillar trim when the airbag is deployed in a vertical direction.
The curtain airbag system disclosed in JP-A No. 2008-230474 is outlined below with reference to FIGS. 7 and 8. FIG. 7 is a schematic side view of a passenger compartment, as seen from the inside of a passenger compartment, where the curtain airbag system is disposed. FIG. 8 is an enlarged sectional view taken along line VIII-VIII of FIG. 7.
As illustrated in FIG. 7, a curtain airbag system 100 mainly includes: an airbag 101 disposed in a folded and retracted state along a roof side rail 115 over the range of a front pillar 111; a center pillar 112; a quarter pillar 114; and an inflator (not illustrated) that, in the event of a side impact, becomes activated to eject gas.
As illustrated in FIG. 8, the airbag 101 of the curtain airbag system 100 is covered at its passenger compartment side with a downwardly curved end 117A of a roof trim 117 that forms a ceiling of the passenger compartment. An upper end 118A of a pillar trim 118 is overlaid on an edge of the end 117A of the roof trim 117 from the inside of the passenger compartment.
The center pillar 112 mainly includes a pillar inner panel 113 and a center pillar section 115A of a side outer panel 115. A roof side rail 116 extends in a longitudinal direction of a vehicle in the inside of a roof side rail section 115B of the side outer panel 115 and is connected at its passenger compartment side with an upper end of the pillar inner panel 113. An inner edge of the roof side rail section 115B and an outer edge of a roof panel 119 are connected with a combining flange formed at the top of the roof side rail 116.
A mounting wall 118B extending upward toward the outside of the passenger compartment is integrally formed on an upper end 118A of the pillar trim 118 provided in the inside of the center pillar 112. In addition, a mounting unit 118C extending downward toward the outside of the passenger compartment from an upper end of the mounting wall 118B is secured to the pillar inner panel 113 using a clip.
An upper wall 118D is formed so as to extend upward from the upper end of the mounting wall 118B. The airbag 101 in a folded state is provided on a guide wall 118E extending obliquely upward toward the outside of the passenger compartment from an upper end of the upper wall 118D. An airbag guide 120 is provided on the upper wall 118D and is configured to cover the upper end 118A of the pillar trim 118 when an upper end 120A thereof is deformed toward the inside of the passenger compartment.
The airbag 101 in a folded state, when receiving a gas supplied from the inflator, becomes inflated and deployed as illustrated by virtual lines. When the airbag 101 has been deployed, the upper end 120A of the airbag guide 120 is deformed toward the inside of the passenger compartment, covering the upper end 118A of the pillar trim 118, as illustrated by the virtual lines. In addition, when the airbag 101 is deployed, a pressing force arising from the inflating and deploying airbag 101 opens up an end 117A of the roof trim 117 toward the inside of the passenger compartment, as illustrated by the virtual lines.
As described above, when the airbag 101 is deployed, the airbag guide 120 is deformed so as to cover the upper end 118A of the pillar trim 118, thereby preventing the rapidly inflating and deploying airbag 101 from coming into direct contact with the upper end 118A of the pillar trim 118. This technique can prevent damage to the upper end 118A of the pillar trim 118, thereby avoiding debris from scattering.
According to JP-A No. 2008-230474, in the event of the deployment, the airbag 101 uses a pressing force arising from its inflation and deployment to open up the end 117A of the roof trim 117 toward the inside of the passenger compartment. Meanwhile, in the center pillar 112, the pressing force exerted toward the inside of the passenger compartment presses against and deforms the upper end 120A of the airbag guide 120 and consequently expands the upper end 120A of the airbag guide 120 and then opens up the end 117A of the roof trim 117. This results in a reduction in the pressing force to open up the end 117A of the roof trim 117 as well as a delay in pressing to open up the end 117A of the roof trim 117, which locally impedes the inflation and deployment of the airbag 101 and produces a temporal variation in the inflation and deployment of the airbag 101, degrading a smooth inflation and deployment of the airbag 101. Also, this may exert a negative effect on the deployment, including a delay in time during which the airbag 101 is deployed.